Sampath Pal Devi grew up in Bundelkhand in Uttar Pradesh and, like many of the women in her community, married young — at 12. She witnessed violence against women as an everyday part of life. It was unsafe for women to go to the outdoor bathrooms at night for fear of assault. At the age of 20, Ms. Sampath Pal fought back, organizing a few women armed with brooms to thrash a notorious wife-beater.

Now in her 40s, she runs the Gulabi Gang. “This country is ruled by men,” she said in her asthma-roughened voice. “No use asking them for help. We women must fight our own battles ourselves.”

Gulabi means “pink” and refers to the color of the saris Ms. Sampath Pal and her band of women wear. The movement has grown from that tiny core of four concerned women to a movement that covers much of rural Uttar Pradesh, one of the most conservative states in India. The brooms have evolved into canes. The Gulabi Gang has thrashed recalcitrant officials and police officers who wouldn’t register cases of domestic violence. It also runs vocational centers that offer practical ways of employment and empowerment for women.